But if these "terrorists" -- this so-called second wave -- are still at large, then it makes sense to ask how viable the plan was at the time, and also to re-examine its viability now, in light of recent changes to airport security.

The following analysis considers the ten factors most likely to cause problems for any potential liquid bomber, and suggests ways in which a second wave of liquid bombers might circumvent these perceived difficulties:

Acetone: Once upon a time you could buy pure acetone in any corner drugstore. It was called "nail polish remover". But nail polish remover nowadays is colored and scented -- not because it needs to be, but because these chemical "impurities" render it useless as a bomb-ingredient. Pure acetone is now extremely tough to find, unless -- hint, hint! -- you just happen to be the purchasing agent for a large pharmaceutical company.

Peroxide: Hydrogen peroxide is easy to find. The corner drugstore will sell you 3% peroxide, but bomb-makers consider this concentration too weak to bother with. They say you should use a concentration of 30% if possible. But where can you get hydrogen peroxide this powerful? Some subterfuge may be required. You may wish to consider an ad in the newspaper: "Earnest young Islamic man seeks concentrated hydrogen peroxide for science fair experiment."

Acid: You'll need highly concentrated hydrochloric or sulfuric acid. If you find these difficult to obtain, you might consider draining your car battery. You're not going to need that car again anyway, right?

Constraints: Under the current restrictions, each passenger can bring just a single one-litre ziplocked clear plastic bag as carry-on luggage, and the liquids in it must be stored in individual bottles of 100ml or less. So getting all the necessary ingredients aboard a plane could pose a problem. But surely you can find a few sympathetic passengers who would be willing to share some of the extra space in their ziplocked baggies.

Glassware: You may be more constrained by glassware than anything else. You'll need a lab-quality beaker to mix your bomb in, and anything larger than two litres will be unwieldy and expensive, not to mention difficult to smuggle aboard. Also, if the beaker can't fit in the sink, you're going to have a problem keeping the reaction cold. So beakers bigger than two litres are out for several reasons.

Time: The reaction takes several hours, and you're planning to do it in the lavatory of an airplane. So you're going to have to choose a flight on which nobody will need to use the facilities, and then, hopefully, no one will notice that something strange is going on. Certainly, if a lineup starts to form outside the door, your prospects for success will diminish considerably.

Temperature: Everything must be kept cold, from the time you add the acteone to the peroxide until your reaction is complete. So you'll need a good supply of ice, and fortunately you have two potential sources: You can have an accomplice carry some onto the plane, and/or you can get ice from the flight crew. We suggest making use of both sources. Your accomplice, of course, should always bring the ice to you directly -- under no circumstances should he ask a flight attendant to "take some more ice to my friend in the bathroom."

Ventilation: The fumes from these chemicals are extremely unpleasant and in some cases debilitating, so adequate ventilation will be necessary. It is unlikely that you will be able to improve the airplane's existing ventilation, so this could be one of your more significant problems. If you find yourself struggling to breathe while mixing the bomb, you can always duck into the passenger compartment for a gasp of fresh air, but if you do this too often, you're likely to attract unwanted attention.

Filtering: The reaction produces explosive crystals rather than an exploding liquid, which is what most people imagine when they hear the term "liquid bomb". In fact, the crystals must be filtered, rinsed and dried before they can be used. So even once the reaction finishes, you still won't be ready to explode anything until you "harvest" your crystals and process them. And by then the plane may have landed already, unless you implore the will of Allah to arrange for heavy fog or maybe even a blizzard, developing in your destination city and spreading to the surrounding area, as close to your ETA as possible.

Yield: You can make about 16 grams of explosive crystals in a two-litre beaker, and as we mentioned, anything bigger than two litres won't fit in the bathroom sink. But you'll need about 250 grams of explosive crystals to knock your airplane out of the sky, so now you need to make another tough decision. Making it all in one big batch would take a lot longer, because you would have to add the acid one drop at a time, so that's not really an option, especially since time is already a factor. Therefore you'll need to recruit a group of teams and have each team make their own crystals. When all the teams are finished, you can combine the crystals for a suitable kaboom. But don't despair. You'll only need 16 teams.

These are the times that try men's souls. The summer soldier and the sunshine patriot will, in this crisis, shrink from the service of their country; but he that stands it now, deserves the love and thanks of man and woman. Tyranny, like hell, is not easily conquered; yet we have this consolation with us, that the harder the conflict, the more glorious the triumph.

Wisdom

And I gave my heart to know wisdom, and to know madness and folly: I perceived that this also is vexation of spirit. For in much wisdom is much grief: and he that increaseth knowledge increaseth sorrow.